Many oscillatory wave drive units have been proposed that excite oscillation in a vibrator and move a moving body pressed against the vibrator. These are positioned as important functional components in optical instruments that must operate particularly precisely. PTL 1 and PTL 2 disclose combining a plurality of straight-type oscillatory wave drive units that can each move a moving body linearly, to move a moving body in two-dimensional directions for use as an image stabilization device.
However, combining a plurality of oscillatory wave drive units has the following serious problem to be solved. When a moving body is moved in some directions, the moving direction of the moving body and the driving direction of some of the plurality of oscillatory wave drive units intersect at right angles or at close to right angles. In this case, the oscillatory wave drive units the driving direction of which intersects with the moving direction at right angles or at close to right angles cannot contribute to driving. The frictional force due to the contact between the moving body and the oscillatory wave drive units interferes with the movement of the moving body and causes energy loss and therefore power loss. When the combination of oscillatory wave drive units is used as a drive unit for an image stabilization device, the properties of the image stabilization device are decreased.
To solve such a problem, PTL 1 and PTL 2 disclose exciting oscillation in oscillatory wave drive units in the direction in which the oscillatory wave drive units are pressed against a moving body, to reduce frictional force and to reduce power loss.